Core Topics in General & Emergency Surgery: Companion to Specialist Surgical Practice (60 page)
Read Core Topics in General & Emergency Surgery: Companion to Specialist Surgical Practice Online
Authors: Simon Paterson-Brown MBBS MPhil MS FRCS
Kenneth D. Boffard
In 1988, without organised trauma care, some 20–35% of patients who reached hospital alive in the UK died unnecessarily,
1
and even in a recent study of the NHS, almost 60% of patients received a standard of care that was considered less than good practice.
2
In the now classic study of trauma centres versus non-trauma centres in California published in 1979, West et al. demonstrated that the majority of preventable deaths resulted from unrecognised, and therefore untreated, intra-abdominal haemorrhage.
3
Approximately 6% of all patients with blunt abdominal trauma will require laparotomy, primarily for haemorrhage from solid-organ injuries. Penetrating torso trauma poses its own problems, especially with regard to whether the peritoneal cavity has actually been penetrated, whether intra-abdominal injury has occurred and, in the presence of competing injuries, the decision-making required for best management.
Mackersie et al., in an evaluation of 3223 patients with blunt trauma, found that the risk of abdominal injury was significantly increased in the presence of an arterial base deficit of 3 mmol/L or more, the presence of major chest trauma, the presence of pelvic fractures or the presence of hypotension.
4
The current ‘gold standard’ for assessment of perfusion following injury is measurement of the serum lactate. Elevated lactate levels indicate organ dysfunction and failure in severely injured trauma patients, and therefore reflect inadequate perfusion and oxygenation of ischaemic tissues.Several studies in critically ill intensive care patients have demonstrated that elevated initial or 24-hour lactate levels correlate significantly with mortality and appear to have a more superior predictive value than corresponding base deficit level changes.
5
,
6
Similarly, prolonged elevation of blood lactate levels has been correlated with increased organ failure and mortality after trauma.
7
Criteria that identify patients at significant risk for abdominal injury, and therefore requiring objective evaluation, are:
Anatomy
major mechanism of injury;
associated major chest injury;
presence of pelvic fracture;
presence of haematuria;
objective physical findings (e.g. tenderness of the abdomen);
impaired sensorium and consequent inability for objective abdominal examination.
Physiology
significant rise in the serum lactate or significant base deficit;
unexplained haemodynamic instability;
unexplained hypovolaemic shock.
Helicopter Emergency Medical Services (HEMS) and its possible association with outcomes improvement continues to be a subject of debate. In an effort to facilitate the academic pursuit of assessment of HEMS utility, in late 2000 the National Association of EMS Physicians (NAEMSP) Air Medical Taskforce reviewed the use of HEMS in both trauma and non-trauma. A more recent literature analysis by Thomas
8
showed, like most HEMS trauma studies, that the crude mortality was much higher in the HEMS patients; however, control for acuity reversed the association and outcomes point estimates favoured HEMS in nine of 10 analyses. Penetrating trauma was the only group for which the non-significant outcome impact was on the side of better outcome with ground EMS. For patients with severe head injuries HEMS response was associated with borderline significant outcome improvement. The authors concluded that HEMS was called for in patients of higher injury acuity with diminished (poorer) vital signs, and that HEMS response resulted in improved outcome for patients with blunt trauma and those with severe head injuries.
In a more recent study of 56 744 inured adults transported to US trauma centres by either ground transport or helicopter, the odds of death were 39% lower in those transported by HEMS, compared to those transported by road, especially in the 18- to 54-year-old age group.
9
A second recent study of 223 475 patients transported by ground and air showed that certain patients transported to level I and II centres by helicopter had an improved odds of survival to hospital discharge.
10
In summary, therefore, HEMS is associated with a reduction in mortality, particularly in patients under 55 years. However, overall survival, especially in those patients with torso or penetrating injury, and patients who are actively bleeding, is best achieved by early control of bleeding. This implies that the time between injury and successful surgical intervention is the single biggest factor in determining a favourable outcome, and in the urban environment this may imply rapid road transport with limited resuscitation en route.
The right patient by the right transport to the right hospital in the right time
.
Dating from 1979,
3
outcomes have been shown to be improved if a regional trauma system is present, and the importance of transporting a patient to an appropriate centre, capable of managing the injuries (actual and potential) in a timely and comprehensive fashion, is well established. The American College of Surgeons Committee on Trauma provides criteria for classification of trauma centres from level I to level IV and definitions for a level I patient.
11
When one or more of the following criteria are present in the trauma patient, he or she is classified as a level I trauma patient and should be transported to the nearest appropriate centre:
confirmed blood pressure (BP) less than 90 mmHg at any time;
respiratory compromise, obstruction and/or intubation;
patients from other hospitals receiving blood to maintain vital signs;
emergency physicians' discretion, especially where there is unexplained hypotension, or the expected need for damage control may exist.
The entire philosophy of the abdominal injury can be summed up by answering the following questions:
Is the abdomen involved in an injury process?
Is a surgical procedure necessary to correct it?
What additional support does the patient require?
In hypotensive patients, the goal is to stop the bleeding, and this includes the rapid determination of whether the abdomen is the cause of the hypotension. If intra-abdominal bleeding
is
the cause, then emergency measures will be needed to control that bleeding. These include emergency transfusion in order to ‘buy time’ or emergency thoracotomy in the emergency room to control the descending aorta and therefore control distal bleeding. Transfusion alone is only a means to an end, and for hypotensive patients with penetrating torso injuries, delay in aggressive fluid resuscitation until rapid operative intervention and control has occurred improves outcome.
12
The often quoted paper by Bickell et al. states that this applies primarily to penetrating trauma of the chest and that other injuries, particularly those involving blunt abdominal trauma, should be assessed. Thromboelastography (TEG) has become a further dynamic point-of-care (POC) standard to optimise clotting ability for haemostasis.
13
,
14
Haemodynamically stable patients without signs of abdominal irritation may undergo a more extended assessment in order to answer the above questions.
Most conventional texts emphasise the need for a careful history and physical examination of the abdomen. In trauma, it is extremely difficult to assess the abdomen, as the history may not be available and all the available physical signs are misleading. Fresh blood is not a peritoneal irritant! Positive clinical findings may be relevant. Negative ones are not!
The mechanism of injury is critically important in assessing the potential for abdominal injury. This information may be obtained from the patient, relatives, police or emergency care personnel. When assessing the patient who has sustained a penetrating injury, pertinent historical information includes the time of injury, type of weapon, number and direction of (especially) bullet wounds (was it an entrance and an exit wound, or two entry wounds with both bullets retained?).
It is unacceptable to withhold analgesia (see also
Chapter 5
). Judicious, properly titrated use of intravenous opiates will not significantly affect the clarity of the history, nor will it ‘mask’ pain, depress cerebration or respiration, or alter the blood pressure. What it will do is make the injury more comfortable for the patient and allow the clinician a much more accurate picture of both the history and the clinical presentation.
The accuracy of physical examination of the abdomen in detecting intra-abdominal injuries is limited. There are many patient factors that contribute to the difficult physical examination, including the presence of other painful distracting injuries, especially if they occur both above and below the abdomen, and an altered level of consciousness as the result of drugs, alcohol or head injury. Recognising these limitations, most trauma surgeons advocate a more objective evaluation of the abdomen in patients at risk for intra-abdominal injury.
The routine radiographs as laid down by the Advanced Trauma Life Support Programme (ATLS®) of the American College of Surgeons are an anteroposterior (AP) chest film and a pelvic film.
15
Abdominal films are not usually useful. If possible (and it is safe to do so), an erect chest radiograph will provide more information than an erect abdominal film in looking for infradiaphragmatic free air (see also
Chapter 5
).
In all cases of penetrating trauma, it is important to appreciate that in the
unstable
patient, the radiograph is unlikely to influence management and the patient requires an immediate laparotomy. However, in the stable patient, useful additional information regarding the track of the bullet can be obtained. It is essential in such a situation to make use of bullet markers to show the entry/exit wounds.
16
These can be simply paper clips taped onto the skin. If there are wounds on both front and back, then one of the paper clips can be unfolded. After the clips are applied to all relevant torso wounds, the radiographs are taken and will give an indication of the track of the bullet, which wound is at the front and which is at the back, and also the presence of other fragments.
The advantages and disadvantages of each of the objective methods of examining the abdomen for injuries are summarised in
Table 13.1
.
Table 13.1
Comparison of diagnostic methods for abdominal injury
| Method | Advantages | Disadvantages |
| Clinical | ||
| Clinical examination | Quick Non-invasive | Unreliable |
| Diagnostic | ||
| Computed tomography ‘Gold standard’ | Organ-specific retroperitoneal information | Patient must be stable Expensive |
| Ultrasound | Quick Non-invasive | User dependent Unhelpful for hollow viscus injury |
| Diagnostic peritoneal lavage | Quick Inexpensive | Invasive Too sensitive Limited specificity |
| Laparoscopy | Organ specific | Painful Anaesthesia required User dependent Patient must be stable |
| Laparotomy | Highly specific | Complications Expensive |
With contrast-enhanced CT (CECT), it is possible both to recognise the organ that is injured and to grade the severity of the injury. Intravascular contrast is essential. There is only limited evidence that enteral (via stomach or rectum) contrast is helpful, and its use may delay the examination. Both intraperitoneal and retroperitoneal injuries can be detected with CECT, and the amount of intra-abdominal blood loss can be estimated. Serial scanning can be used to follow the resolution (or progression) of an injury. The disadvantages of CECT include the need to move the patient to the radiology suite and the time required to perform the scan, although with the introduction of 64-slice spiral scanners, the latter factor has become less important. CT is expensive, there is the potential for allergic reaction to the injected contrast material, or for aspiration of oral contrast (a rare event), and the danger of the radiation dose administered should not be underestimated.
17
It has been estimated that the danger of CT scan-induced cancer may be as high as 2%.
18
Although CT is relatively insensitive in the detection of hollow viscus injuries, a bowel injury (and especially a duodenal injury) is suggested by finding a thickened bowel wall, extraluminal air and the presence of intraperitoneal fluid in the absence of a solid-organ injury.
19
,
20
CT may also miss a pancreatic injury early in its course. The accuracy of CT is generally poor in the detection of diaphragmatic, hollow-organ and mesenteric injuries, and there have been reports of a high incidence of false-negative results.
21
Despite these limitations, however, CT remains the method of choice for objective evaluation of the abdomen in
stable
trauma patients who are likely to have an intra-abdominal injury, and is currently the ‘gold standard’ of investigation.
The sensitivity of ultrasound for the detection of free intraperitoneal fluid in abdominal blunt trauma has been shown to be 81–99%.
22
The disadvantage of ultrasound is its lack of sensitivity for injuries that do not produce blood or peritoneal fluid and the fact that its accuracy is directly related to the experience of the ultrasonographer. Nonetheless, surgeons can be taught to perform and interpret ultrasound examinations rapidly and accurately, with a sensitivity/specificity and accuracy each over 90%.
23
This diagnostic method has particular appeal in paediatric trauma patients and in the injured gravid patient.
In most centres, ultrasound has replaced diagnostic peritoneal lavage (DPL) for evaluation of the unstable patient following blunt trauma. However, the role of ultrasound in the assessment of penetrating abdominal trauma is still controversial, since the examination will miss small amounts of intraperitoneal fluid.
Root et al. introduced DPL as a method of evaluation of the abdomen some 50 years ago,
24
and while it has frequently been superseded by more sophisticated (and potentially more expensive) techniques, it remains the standard against which all other diagnostic examinations are judged. The main advantage of DPL is that it can be performed quickly and with few complications by relatively inexperienced clinicians. DPL is also reproducible, as well as highly sensitive and specific for the detection of abdominal blood (> 97%), but it does not identify the organ of injury.
Injuries of the retroperitoneum will be missed by DPL, and the presence of pelvic fractures may lead to a false-positive result.
A DPL is generally considered as positive if:
red cell count is > 100 000 cells/mm
3
;
white cell count is > 500/mm
3
;
there is amylase or bowel content in the lavage return.
However, if surgeons are committed to operating on all patients with positive DPL the ability to manage patients non-operatively may be lost.The lavage is therefore regarded as an indicator of the presence of abdominal pathology, but not necessarily an indication for surgery (see section on non-operative management below).
Laparoscopy has yet to find its role in the evaluation of the patient with blunt abdominal trauma.
25
With few exceptions, laparoscopy requires general anaesthesia, is expensive and has the potential to create a tension pneumothorax
26
or air embolus during insufflation. Laparoscopy in penetrating injury has been reported with the successful repair of injuries of the diaphragm and stomach.
27
An additional drawback of diagnostic laparoscopy currently is the relative cost compared with other modalities, especially those performed at the bedside, such as ultrasound. The technique should only be used on relatively stable patients, and laparoscopy is still limited in its ability to detect penetrating intestinal injury, especially in the hands of an operator unskilled in the specific techniques required for elucidation of intra-abdominal injury. Currently, laparoscopy is most useful in the patient with penetrating abdominal trauma when there is a question of peritoneal penetration or diaphragmatic injury. The diaphragm is also an area where delay or missed diagnosis dramatically increases the morbidity.
28
Laparoscopy can identify not only clinically unsuspected diaphragm injuries but also other injuries that have been ‘missed’ by other diagnostic tests.
Diagnostic laparoscopy does not confer any advantages or improvements over other techniques when it comes to investigation of retroperitoneal injuries to organs such as the duodenum and pancreas, and CT remains more accurate in this regard.
Mandatory laparotomy:
While laparotomy remains the most appropriate therapy for an unstable patient with obvious abdominal trauma, a non-therapeutic laparotomy is not necessarily benign. In a prospective study of unnecessary laparotomies performed in 254 trauma patients, complications occurred in 41% of patients, and included atelectasis, postoperative hypotension, pleural effusion, pneumothorax, prolonged ileus, pneumonia, surgical wound infection, small-bowel obstruction and urinary infection.
29
Many centres still practise a policy of
mandatory laparotomy
for abdominal gunshot wounds because of the higher morbidity associated with delayed diagnosis. However, Ross et al.
30
reported a negative laparotomy rate (absence of injury) of 12% in gunshots, 23% in stab wounds and 6% in blunt trauma, suggesting that there is a more accurate investigation of the abdomen in blunt trauma.
Selective laparotomy (i.e. selective conservatism) in penetrating injury:
Several studies have considered the possibilities of selectively treating certain patients by observation only, even when a laparotomy seems to be required. Two South African studies reviewed
selective conservatism
in the management of abdominal gunshot wounds. Muckart et al. reported no delayed laparotomies or morbidity, with only a 7% negative laparotomy rate,
31
and Demetriades et al. found a delayed laparotomy rate of 17%.
32
It is obvious that the decision not to operate should be carefully considered and, if taken, meticulous and repeated re-examination of the patient for changing abdominal signs should be performed. A general dictum should be that the more there is uncertainty in the assessment, or the more inexperienced the assessor, the more aggressive should be the tendency towards laparotomy.